Technically, it "upscales" everything to 4k, but I watch more 1080 sources. I am not real sure that I watch much 1080p (Bluray). A lot of stations broadcast at 1080i/720p. I haven't really looked into each channel, so that being said, I probably watch more 4k than 1080p, but I lumped everything from Comcast into the 1080p bucket (since I believe that is what you were asking).
The move to 4k will take a long, long time for network TV. I watch Amazon and Youtube in 4k (though some of Youtube is 4k upconverted from lower resolution sources), though.